Question

The molten wax in investment casting is at a pressure of _______

(a) 1 bar

(b) 4 bar

(c) 12 bar

(d) 26 bar

This question was addressed to me in class test.

My doubt stems from Casting Processes in chapter Testing of Materials, Foundry & Powder Metallurgy of Engineering Material & Metallurgy

Answer 1

The correct answer is (b) 4 bar

To elaborate: In investment casting, wax or plastic is injected under pressure into the die as the pattern is used to make a die out of soft material. The molten wax is slightly above its melting point and injection pressure is above 4 bar. If it is a plastic material like polystyrene, the injection pressure may be of the order of 35 bar with higher temperature.